AIR PRESSURE AIR PRESSURE AIR PRESSURE MEASURE OF

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AIR PRESSURE

AIR PRESSURE

AIR PRESSURE • AIR PRESSURE: MEASURE OF THE FORCE WITH WHICH AIR MOLECULES PUSH

AIR PRESSURE • AIR PRESSURE: MEASURE OF THE FORCE WITH WHICH AIR MOLECULES PUSH ON A SURFACE. • AIR PRESSURE IS GREATEST AT THE SURFACE OF EARTH BECAUSE THERE IS THE MOST ATMOSPHERE ABOVE

AIR PRESSURE IS DEPENDENT ON DENSITY • DENSER AIR WILL HAVE A HIGHER AIR

AIR PRESSURE IS DEPENDENT ON DENSITY • DENSER AIR WILL HAVE A HIGHER AIR PRESSURE- MORE AIR MOLECULES IN A GIVEN SPACE • LESS DENSE AIR WILL HAVE A LOWER AIR PRESSURE- FEWER AIR MOLECULES TO PUSH Less Dense= fewer particles More DOWN. Dense= more particles to push down on you

AIR PRESSURE IS AFFECTED BY: • 1 - ELEVATION (OR ALTITUDE) • 2 -

AIR PRESSURE IS AFFECTED BY: • 1 - ELEVATION (OR ALTITUDE) • 2 - TEMPERATURE • 3 - WATER CONTENT

IMPACT OF ELEVATION ON AIR PRESSURE • AS YOU MOVE UP THROUGH THE ATMOSPHERE,

IMPACT OF ELEVATION ON AIR PRESSURE • AS YOU MOVE UP THROUGH THE ATMOSPHERE, AIR PRESSURE DECREASES. • THERE ARE FEWER AIR MOLECULES ABOVE, SO THE FORCE OF THE AIR WILL BE LESS.

IMPACT OF WATER CONTENT, OR HUMIDITY, ON AIR PRESSURE • MOIST AIR IS LESS

IMPACT OF WATER CONTENT, OR HUMIDITY, ON AIR PRESSURE • MOIST AIR IS LESS DENSE THAN DRY AIR, AND THEREFORE HAS A LOWER AIR PRESSURE. • A WATER MOLECULE HAS LESS MASS THAN OTHER MOLECULES THAT MAKE UP THE AIR. N O O H 2 O N H 2 O Weighs less since H 2 O is lighter than Nitrogen and Oxygen

IMPACT OF TEMPERATURE ON AIR PRESSURE • WARM AIR IS LESS DENSE THAN COLD

IMPACT OF TEMPERATURE ON AIR PRESSURE • WARM AIR IS LESS DENSE THAN COLD AIR. THEREFORE, WARM AIR HAS A LOWER PRESSURE • THE MOLECULES IN WARM AIR ARE MOVING FAST AND ARE SPREAD FARTHER APART. Warm Air Cold Air

BAROMETER • THE PIECE OF EQUIPMENT USED TO MEASURE AIR PRESSURE IS A BAROMETER

BAROMETER • THE PIECE OF EQUIPMENT USED TO MEASURE AIR PRESSURE IS A BAROMETER Mercury Barometer Aneroid Barometer

MERCURY BAROMETER

MERCURY BAROMETER

AIR PRESSURE AFFECTS THE WEATHER • AIR PRESSURE IN A WEATHER SYSTEM REFLECTS THE

AIR PRESSURE AFFECTS THE WEATHER • AIR PRESSURE IN A WEATHER SYSTEM REFLECTS THE AMOUNT OF WATER IN THE AIR, WHICH AFFECTS THE WEATHER. Low air pressure usually results in Bad weather: stormy, cloudy, overcast. High air pressure usually results in Good weather: clear skies, no precipitation

LOW PRESSURE • USUALLY BRING CLOUDY AND WET DAYS. • IN THE NORTHERN HEMISPHERE,

LOW PRESSURE • USUALLY BRING CLOUDY AND WET DAYS. • IN THE NORTHERN HEMISPHERE, A LOW-PRESSURE SYSTEM FORCES WINDS TO SPIRAL COUNTERCLOCKWISE. • AIR IS FORCED TOWARD THE CENTER AND UP. • AS THE AIR RISES, IT COOLS • COLD AIR CAN’T HOLD AS MUCH WATER VAPOR AS WARM AIR, SO THE WATER CONDENSES OR COMES TOGETHER, TO FORM CLOUDS. • WHEN THE WATER DROPLETS JOIN TOGETHER AND

HIGH PRESSURE • USUALLY BRING CLEAR AND CALM CONDITIONS • IN THE NORTHERN HEMISPHERE,

HIGH PRESSURE • USUALLY BRING CLEAR AND CALM CONDITIONS • IN THE NORTHERN HEMISPHERE, HIGHPRESSURE SYSTEM WINDS SPIRAL CLOCKWISE, MOVING FROM THE CENTER OUTWARD. • TO REPLACE THE AIR THAT FLOWS OUT OF THE STORM’S CENTER, MORE AIR IS SUCKED DOWN FROM UP HIGHER IN THE ATMOSPHERE.

AIR PRESSURE ON A WEATHER MAP • AREAS OF HIGH AND LOW PRESSURE ON

AIR PRESSURE ON A WEATHER MAP • AREAS OF HIGH AND LOW PRESSURE ON SHOWN ON A WEATHER MAP WITH AN H OR AN L.